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Speaker 1: Hey, welcome to Stuff to Blow Your Mind. My name

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Speaker 1: is Robert Lamb and I'm Joe McCormick, and it's Saturday.

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Speaker 1: Time to dig into the vault for an older episode

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Speaker 1: of the show. This is our episode on the Silurian hypothesis,

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Speaker 1: originally published January. I hope you enjoy Welcome to Stuff

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Speaker 1: to Blow Your Mind production of My Heart Radio. Hey,

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Speaker 1: welcome to Stuff to Blow Your Mind. My name is

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Speaker 1: Robert Lamb and I'm Joe McCormick, and today we're going

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Speaker 1: to be talking about a subject that I've actually had

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Speaker 1: on the radar for a while. This is something that

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Speaker 1: was making the rounds on science blogs a few years back,

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Speaker 1: and it has been suggested by a number of different listeners.

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Speaker 1: So I'm glad we're finally coming around to it. I

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Speaker 1: think I had some hesitation for a while that I

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Speaker 1: want to briefly explain right at the beginning here. But

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Speaker 1: today we're gonna be talking about an idea known as

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Speaker 1: the Silurian hypothesis. Uh. And just to give you a

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Speaker 1: little bit of background knowledge, we spent several minutes before

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Speaker 1: recording today trying to look up how they pronounced silurian

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Speaker 1: on Doctor Who because I was like, sure they might

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Speaker 1: use some kind of British English variation where they say Silurian,

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Speaker 1: but but a last we could not ever get the

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Speaker 1: doctor to say it right. I watched I think, an

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Speaker 1: entire scene where one of the more recent doctors was

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Speaker 1: chatting with a Silurian or Silurian out out of your Will,

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Speaker 1: and they they it was like they were trying not

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Speaker 1: to say it, like if they said it, one would

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Speaker 1: would pop up and and crawl out of the screen

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Speaker 1: or something. Uh they used they referred to another alien race.

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Speaker 1: There wasn't even in the scene, and I don't even

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Speaker 1: think was part of that episode. And then in all

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Speaker 1: these other terms, but yeah, they were just trying to

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Speaker 1: mess with me. So this is a topic that I

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Speaker 1: have been interested in covering for quite a while. It's

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Speaker 1: it's been a few years now, but Rob, when you

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Speaker 1: suggested it, I realized that I'd always been hesitating and

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Speaker 1: not wanting to quite go ahead with it. And I

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Speaker 1: think I realized the reason for that, which is that

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Speaker 1: when I saw people mentioning this paper on the internet,

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Speaker 1: it was clear to me that a lot of them

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Speaker 1: were getting exactly the wrong takeaway from it, Like they

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Speaker 1: were latching onto a very shallow understanding of the concept

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Speaker 1: and and running off in a in a very different

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Speaker 1: direction than the authors intended. Not only a different direction

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Speaker 1: than they intend, but a direction they specifically say do

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Speaker 1: not go in, and specifically say that they are not

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Speaker 1: trying to to make yeah. Uh So, to to clarify

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Speaker 1: what we're talking about here, the Silurian hypothesis paper begins

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Speaker 1: with a fascinating question, in the words of the author's quote,

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Speaker 1: if an industrial civilization had existed on Earth many millions

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Speaker 1: of years prior to our own era, what traces would

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Speaker 1: it have left and would they be detectable today? That

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Speaker 1: that's the question at the heart of this paper. And

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Speaker 1: obviously this is a tantalizing premise. You know, it sets

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Speaker 1: your mind racing with images of impossibly weird organisms, you know,

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Speaker 1: like land dwelling octopi and stuff in the in their

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Speaker 1: own weird cities, and and what kind of technology would

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Speaker 1: they have? Things that are as alien as anything you

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Speaker 1: could imagine on another planet, except they would have all

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Speaker 1: been from here, native to planet Earth, dating back millions

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Speaker 1: of years into prehistory. But while this is a really

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Speaker 1: attractive imaginative exercise, I think the first order of business

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Speaker 1: when talking about this subject is to be clear that

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Speaker 1: the Silurian hypothesis paper is about coming up with a

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Speaker 1: framework for detecting physical traces of industrial civilizations and understanding

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Speaker 1: how long those traces last. So it's about trying to

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Speaker 1: say what are the right questions to ask when you're

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Speaker 1: when you're looking at a planet and saying, how could

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Speaker 1: we tell if there had been a civilization on this

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Speaker 1: planet a long time ago. It is not a paper

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Speaker 1: arguing that there was in fact a lost civilization deep

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Speaker 1: in Earth's past. So it's not evidence for lizardman, ancient aliens,

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Speaker 1: Graham Hancock, Junk Atlantis, or any of that stuff. But

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Speaker 1: I would say in its true form, it is a

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Speaker 1: really interesting question. Yeah, and at hard this episode is

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Speaker 1: is not going to be about scientific evidence for lizardman

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Speaker 1: civilizations in the Hollow Earth. So if you're looking for that,

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Speaker 1: this is this is not the episode for you. But yeah,

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Speaker 1: what I love about it is that it takes this

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Speaker 1: sort of fantastic idea and then examines it reasonably, and

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Speaker 1: that examination illuminates some very interesting geologic, climatic and astrophysical considerations. So,

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Speaker 1: you know, setting aside pseudoscience and pseudo archaeology here. But

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Speaker 1: on the other hand, I think if you if you're

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Speaker 1: looking for some sci fi fund this topic in this episode,

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Speaker 1: well also still engage you. Um. But it is interesting

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Speaker 1: how from a certain perspective you can imagine people being

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Speaker 1: drawn into it by just sort of this sci fi idea,

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Speaker 1: this idea that does lean lend itself well to sort

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Speaker 1: of conspiracy theorist mindsets, and then realizing actually, this paper

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Speaker 1: is about geology and uh and uh and in the

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Speaker 1: last year of our planet and also uh, I guess

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Speaker 1: kind of you know, in many cases, kind of a

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Speaker 1: downbeat message about the lasting impact of human technology on

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Speaker 1: our planet. And on the other hand, too, how forgettable

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Speaker 1: we may be from the standpoint of geological history. Yeah,

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Speaker 1: so if you're on board for all of that, you've

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Speaker 1: come to the right place. So real quick, I do

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Speaker 1: want to just discuss the Doctor Who reference here, since

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Speaker 1: since uh the author's Schmidt and Frank took the name

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Speaker 1: for the hypothesis from the Doctor Who species the Silurians

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Speaker 1: who first popped in the nineteen seventies series Doctor Who,

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Speaker 1: and these Silarians, I think now you've got me saying Silarians. Oh,

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Speaker 1: I'm sorry, I'm probably well. It gets even worse because

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Speaker 1: so they take the name of the hypothesis from this

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Speaker 1: Doctor Who series where these creatures show up. But then

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Speaker 1: they say explicitly in the paper, you know, the range

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Speaker 1: we would really be looking at would actually be after

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Speaker 1: the Silurian geologic periods. Silurian period is something that's like

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Speaker 1: a roughly twenty million year period. That's more than four

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Speaker 1: hundred million years ago. I don't know, it's like four

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Speaker 1: hundred and forty something to four hundred and twenty something,

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Speaker 1: I think roughly. But if you were seriously looking for

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Speaker 1: evidence of lost civilizations in Earth's ancient past, you'd probably

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Speaker 1: be looking for things like after about four hundred million

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Speaker 1: years ago, coming you know, forward in time from the

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Speaker 1: Devonian period, when you could have the reasonable biological basis

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Speaker 1: for land dwelling animals that might have evolved complex technological intelligence. Yes, uh,

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Speaker 1: but at any rate. In Doctor Who, especially in that

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Speaker 1: original nineteen seventy uh appearance, the Silurians are these kind

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Speaker 1: of lizard men um. They factor into this plot with

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Speaker 1: the Third Doctor played by John Perkway who lived nineteen

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Speaker 1: nine six, and then they subsequently pop up again with

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Speaker 1: the fifth Doctor played by Peter Davison and the eleventh

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Speaker 1: Doctor played by Matt Smith, and then more recently the

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Speaker 1: third teenth Doctor played by Jody Whittaker. So this is

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Speaker 1: just the TV show. I can't speak to the various

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Speaker 1: books and audio dramas that have come out, and their

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Speaker 1: look has changed throughout the film. Um. You know, they are,

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Speaker 1: in essence, this cold blooded, prehistoric reptile like species with

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Speaker 1: significant technological advancement that they I think they end up

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Speaker 1: entering various states of suspended animation to avoid uh you know,

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Speaker 1: major changes on Earth, changes to the climate, etcetera. Um,

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Speaker 1: and then they re emerge and encounter the Doctor. Um.

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Speaker 1: So yeah, they're They're one of the many interesting alien

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Speaker 1: and otherworldly species that pop up. Uh. Though I guess

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Speaker 1: with the Silurians one of the key things is that

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Speaker 1: they're they're not pure aliens. They're they're sort of the originals.

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Speaker 1: There are their original terrans, original earthlings, uh, that are

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Speaker 1: then encountered by these evolved apes that come much later.

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Speaker 1: I mean to to them, we are the aliens, yeah, right,

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Speaker 1: were like these weird future creatures. Uh the image you

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Speaker 1: would tell And I gotta be honest, I'm not a hoovoid,

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Speaker 1: so I don't know the lore. But the picture you're

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Speaker 1: showing me of the Silurians, they look like they look

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Speaker 1: like if the world was all creature from the Black

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Speaker 1: Lagoon and there was a leather face of the creature

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Speaker 1: from the Black Lagoon civilization. Yeah. I mean, they're definitely

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Speaker 1: Doctor Who creatures of this era, which which I tend

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Speaker 1: to love these costumes. I know they were working with

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Speaker 1: with with with budget limitations here, but yeah, the the

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Speaker 1: aliens and robot of this era really really called me. Now.

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Speaker 1: You said they look kind of fish like. Bear in mind,

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Speaker 1: and I'm sure some Doctor Who listeners Doctor Who viewers

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Speaker 1: will will will chime in here. But I believe they

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Speaker 1: are related to another species that pops up on the

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Speaker 1: show that live in the water. I think they're like

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Speaker 1: the sea devils or something. Um, but these guys are

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Speaker 1: not aquatic in nature. I think I got that right.

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Speaker 1: The seed of Oh wait, this is that like a

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Speaker 1: bunch of intelligent euryptorids or something something like that. Yeah, alright,

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Speaker 1: so this is two thousand eighteen paper, the Silurian hypothesis.

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Speaker 1: Would it be possible to detect an industrial civilization in

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Speaker 1: the Geological Record. This was published in the journal International

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Speaker 1: Journal of Astrobiology. UH. It draws its name from that

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Speaker 1: Doctor Who episode, and the authors here that they point

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Speaker 1: out that they may be the first to seriously consider

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Speaker 1: whether a technologically advanced civilization could have evolved prior to

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Speaker 1: Homo sapiens on Earth, though the authors due stress that

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Speaker 1: this is a to the best of the knowledge situation,

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Speaker 1: So you know, it's entirely possible somebody was batting around

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Speaker 1: the idea of previously, but this may be the first,

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Speaker 1: and certainly this was this one really made a splash

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Speaker 1: when it came out. Okay, So the two authors here

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Speaker 1: would be Adam Frank and Gavin A. Schmidt right and

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Speaker 1: Frank is a is a physicist and astronomer, and Schmidt

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Speaker 1: is a climate scientist right right. Schmidt is a climatologist,

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Speaker 1: climate model and director of the NASA Goddard Institute for

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Speaker 1: Space Studies in New York and co founder of the

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Speaker 1: award winning climate science blog Real Climate. Frank is a physicist, astronomer,

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Speaker 1: and writer whose work has appeared in such publications as

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Speaker 1: The New York Times and NPR. And I believe we've

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Speaker 1: actually referenced his work on the podcast before. Uh. He

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Speaker 1: also has a book. He has a few books, including

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Speaker 1: The Constant Fire, The End of the Beginning, and Light

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Speaker 1: of the Stars. Those are all nonfiction science books, of course.

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Speaker 1: So to be clear, we're talking about two very legitimate

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Speaker 1: scientists and science communicators, not you know, not a couple

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Speaker 1: of of quacks who were staring into the hollow Earth

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Speaker 1: or anything. So the authors here begin with a very

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Speaker 1: reasonable consideration of the search for intelligent life elsewhere in

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Speaker 1: the universe. Uh. And then this is something we've we've

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Speaker 1: touched on the show plenty of times before. Ours is

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Speaker 1: the only model of life, but we generally consider technological

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Speaker 1: advancement to be a hallmark of intelligent life. And more

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Speaker 1: to the point, something we can search for signs of, uh,

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Speaker 1: concerning other worlds and other star systems. Uh. You know,

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Speaker 1: and anytime you can you can figure out how to

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Speaker 1: look for signs of of advanced and expansive energy harvesting

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Speaker 1: or consumption. That might be a way for us to

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Speaker 1: tell if there's something else out there that is significantly advanced, right,

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Speaker 1: and it also might be a simple prerequisite for contact

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Speaker 1: because uh, they're talking about so that They started off

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Speaker 1: by looking at this as an astrobiology question. You know,

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Speaker 1: you're you're looking for signs of life elsewhere in the universe,

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Speaker 1: and of course, the the search for intelligent life in

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Speaker 1: the universe, in practical terms, what's accessible to us, really

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Speaker 1: boils down to the search for life capable of Harvard

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Speaker 1: harnessing radio technology within our galaxy. You know, you could

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Speaker 1: probably find maybe chemical biosignatures in in the atmospheres of

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Speaker 1: exoplanets that would give you an indication that there's some

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Speaker 1: kind of life there, maybe bacterial in nature or whatever.

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Speaker 1: But if you're looking for intelligent life, you're you're probably

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Speaker 1: talking about radio of some kind, right, And so the

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Speaker 1: kinds of civilizations that develop radio communication technology would fall

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Speaker 1: under the classification of industrial civilizations. And these are what

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Speaker 1: author the authors define as civilizations that have the ability

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Speaker 1: to harness energy on a global scale. And they bring

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Speaker 1: up how this actually feeds into one of the the

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Speaker 1: recurring characters in in the astrobiology literature, the Drake equation.

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Speaker 1: That's right, Yeah, they bust out the Drake equation, and

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Speaker 1: of course consider how how some of the takeaways relate

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Speaker 1: to Earth, especially the notion that over the course of

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Speaker 1: a planet's existence, multiple industrial civilizations can fear radically arise

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Speaker 1: over the span of time that life exists there, And

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Speaker 1: then we have to factor in questions over you know,

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Speaker 1: how many times life itself may have evolved or started

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Speaker 1: out on Earth before our last universal common ancestors got going,

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Speaker 1: the possibility of a shadow biosphere, and the idea that

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Speaker 1: species like dolphins may suggest independent evolutions of intelligence on Earth. Um,

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Speaker 1: you know, so we're left with this idea that, yeah, theoretically,

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Speaker 1: given the footprint of life on Earth, you could have

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Speaker 1: had multiple intelligences uh evolved and arise during that time period.

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Speaker 1: Because that's certainly what the Drake equation UH seems to

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Speaker 1: allow for concerning other worlds. Well, yeah, and I you know,

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Speaker 1: so I kind of love the Drake equation. You know,

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Speaker 1: it's a famous tool that I really enjoy thinking about

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Speaker 1: because because it does the job of taking a question

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Speaker 1: that seems like we could not possibly answer it. The

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Speaker 1: question is how many active technological civilizations are there in

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Speaker 1: the Milky Way galaxy? And you know, if you're being

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Speaker 1: honest with yourself, the correct answer to that is how

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Speaker 1: the hell should I know? Like, there's no way to

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Speaker 1: answer that question at all. But what the Drake equation

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Speaker 1: does is break that unanswerable question down into a number

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Speaker 1: of other questions that you then multiplied together to get

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Speaker 1: an estimated number. And many of those smaller questions themselves

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Speaker 1: could perhaps be answered, and in fact, some of them

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Speaker 1: have been answered since the Drake equation was first formulated.

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Speaker 1: Uh So, So it decomposes an unsolvable problem of are

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Speaker 1: there aliens out there? And if so, how many, into

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Speaker 1: a series of smaller problems, at least some of which

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Speaker 1: are solvable, maybe all of which are. You know, you

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Speaker 1: could come up with some kind of reasonable guess about.

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Speaker 1: And so the classic formulation of the Drake equation is

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Speaker 1: to get your number of civilizations in in the Milky way,

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Speaker 1: you would multiply a bunch of different terms together. So

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Speaker 1: one is the rate of average the average rate of

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Speaker 1: star formation. You know, how much do you get stars

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Speaker 1: times the fraction of stars that have planets times the

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Speaker 1: average number of planets per star times the fraction of

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Speaker 1: planets that develop life times the portion of those life

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Speaker 1: systems that gain intelligence, times the portion of those intelligent

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Speaker 1: life systems that develop technological means to communicate times And

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Speaker 1: then here's a really interesting term, quote the length of

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Speaker 1: time l over which such civilizations released detectable signals. And

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Speaker 1: it's this very last term that I think very often

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Speaker 1: gets overlooked by people who are thinking about, you know,

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Speaker 1: are there aliens out there, and how could we know?

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Speaker 1: I think we often tend to assume that, well, once

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Speaker 1: there are aliens with technological means to communicate, that's just

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Speaker 1: like a you know, progress only extends from their civilizations

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Speaker 1: just continue to get bigger and their capabilities expand, and

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Speaker 1: they spread out from there. But I don't know that

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Speaker 1: there could be severe limitations on the length of a

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Speaker 1: radio receptive or radio broadcasting civilist nation. Maybe they only

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Speaker 1: exist for a few hundred years. Because one thing we

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Speaker 1: know is that our technological civilization is just a tiny

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Speaker 1: blip on the history of planet Earth, even a tiny

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Speaker 1: blip on the history of life on planet Earth. Earth

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Speaker 1: is four point five billion years old. There's been life

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Speaker 1: on Earth for most of that time. Uh. The authors

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Speaker 1: here estimate that there has been complex life on Earth's

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Speaker 1: land surface for only about four hundred million years, So

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Speaker 1: that's only a fraction of the entire history of Earth.

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Speaker 1: But that but four hundred million years is still a

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Speaker 1: gargantuan amount of time compared to the length of human civilization.

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Speaker 1: They say, industrial civilization, you know, by their metric, has

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Speaker 1: probably existed for only about three hundred years. This is

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Speaker 1: since roughly the beginning of mass production methods for for things.

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Speaker 1: And so if humans were wiped out by a global

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Speaker 1: mass extinction of some kind in the near future, our

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Speaker 1: industrial civilization would just be this tiny little splinter, this

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Speaker 1: blip of three hundred years on a history of a

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Speaker 1: currently four point five billion year old planet. Yeah, and

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Speaker 1: so from there we get into the question, Okay, if

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Speaker 1: if you have an industrial civilization like this it is

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Speaker 1: just a blip, would we be able to see it?

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Speaker 1: And if we could see it, what would we look for?

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Speaker 1: And this is you know, this is pretty much the

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Speaker 1: meat of the paper here analyzing this sort of question,

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Speaker 1: which which is great because it again it gets into

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Speaker 1: sort of uh, you know, sci fi friendly concepts. It's

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Speaker 1: a useful in considering the evolution of life and the

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Speaker 1: existence of intelligent life on other worlds. And it also

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Speaker 1: shines a light on what we're doing now and where

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Speaker 1: we are and and I think also, uh, you know,

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Speaker 1: illustrates nicely illustrates this idea that um that that the

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Speaker 1: technology is not just this um that this this this

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Speaker 1: ramp to Star Trek, you know, or this ramp to

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Speaker 1: the culture or any of our more optimistic sci fi

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Speaker 1: dreams like there are there are severe challenges. Uh. And

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Speaker 1: of course there's there's always the risk of extinction. That's

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Speaker 1: exactly right. And one thing that's funny is we don't

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Speaker 1: know whether the rise of technological civilization should generally be

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Speaker 1: understood as, on average, a linear process where it just

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Speaker 1: sort of goes in one direction and keeps going in

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Speaker 1: that direction, or whether it should be understood as, on

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Speaker 1: average a cyclical process where you get a rise in

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Speaker 1: technological civilization and then it disappears for some reason. You

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Speaker 1: can imagine what some of those reasons might be, um,

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Speaker 1: and uh, and then maybe rises again out of the

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Speaker 1: out of the same biosphere. I mean. Either one I

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Speaker 1: think is is a perfectly plausible model to entertain is

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Speaker 1: like what usually happens in the universe. Uh. And we

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Speaker 1: just don't have the Uh, we don't have the evidence

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Speaker 1: to really have an opinion on that. Yeah, I mean

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Speaker 1: a lot of it just comes back to the fact

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Speaker 1: that again we are the only model of intelligent life

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Speaker 1: and certainly technologically advanced tech, um, intelligent life that we

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Speaker 1: have to look at. So we have nothing to compare

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Speaker 1: us to. Yeah, and we don't know what's going to

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Speaker 1: happen to us in the long run, right, So, uh, well,

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Speaker 1: let's get into the I guess the sort of the

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Speaker 1: first part of the paper. And I do want to

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Speaker 1: drive home that if you want to just go right

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Speaker 1: to the paper yourself and dive in. Um, you just

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Speaker 1: do a search for the title and you can find

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Speaker 1: it hosted on NASA. They have a NASA has a

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Speaker 1: has a PDF of this that's very easily accessible. Uh.

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Speaker 1: You can also read it in full on the Cambridge

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Speaker 1: University Press website, which I think is the press behind

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Speaker 1: the journal, the International Journal Journal of Vester Biology. And yeah,

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Speaker 1: so it's all on their end with the references hyperlinked

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Speaker 1: and all that, which is nice. Yes, yeah, absolutely so

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Speaker 1: if you hit a paywall, don't don't give up. It's

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Speaker 1: out there. Um. And I believe Adam Frank also wrote

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Speaker 1: a piece for What the Atlantic where he nicely summarizes

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Speaker 1: some of the ideas here. Oh yeah, and he also

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Speaker 1: tells a funny story about how they arrived at writing

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Speaker 1: the paper because I think he says, uh, he showed

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Speaker 1: up in Gevin Schmidt's office to talk about UM, to

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Speaker 1: talk more about astrobiology, like Drake equation type questions, and

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Speaker 1: he's like, okay, so we we we know we've got

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Speaker 1: one industrial civilization on Earth. And then Schmidt responded by saying,

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Speaker 1: how do we know we're the only one? I think

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Speaker 1: just hitting that early like wall, They're like wow, And

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Speaker 1: then that turned into the paper, Yeah, and it's it's

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Speaker 1: it's quite a paper. Thank So let's see, let's get

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Speaker 1: into the first part of it, which I think you

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Speaker 1: can loosely think of it's just sort of a look

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Speaker 1: at the limits of our vision. So they point out

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Speaker 1: that for the last two point five million years, uh,

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Speaker 1: there's widespread physical evidence of things like climate change, soil horizons,

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Speaker 1: this is where one layer of soil differs from Belower above,

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Speaker 1: speaking to changes recorded in the soil, as well as

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Speaker 1: archaeological evidence of non Homo sapiens cultures such as the Neanderthals.

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Speaker 1: And this two point five million year period is known

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Speaker 1: as the Quaternary. Now, going back before the Quaternary again

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Speaker 1: more than two point five million years ago, the land

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Speaker 1: evidence is harder to come by. You have to depend

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Speaker 1: on drilling, mining, and occasional exposed sections of the earth.

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Speaker 1: Even in the ocean sentiment evidence apparently only goes back

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Speaker 1: to around one seventy million years ago. Yeah, And I

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Speaker 1: think for me this was actually one of the most

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Speaker 1: interesting parts of the paper because I would say, if

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Speaker 1: you just go by standard intuition, a person might think, uh,

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Speaker 1: you know, if there had been a civilization on Earth,

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Speaker 1: you know, a two million years ago or something like that. Uh,

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Speaker 1: would wouldn't that just be completely obvious, Like we'd see

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Speaker 1: evidence of it all around us. Would there be ruins

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Speaker 1: and all that, you know, their their stone hinges, their

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Speaker 1: skyscrapers and everything like that. Actually it's not. It might

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Speaker 1: not be as obvious as you might think. In fact,

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Speaker 1: the evidence of it could be rather scarce. And this

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Speaker 1: runs counter to our side five imaginings, right, because when

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Speaker 1: you encounter elder civilizations and in other works like there's

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Speaker 1: usually some sort of a ruin or a vault or

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Speaker 1: some sort of mysterious monolith or something like the idea

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Speaker 1: that the elders would just be gone entirely, like just erased,

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Speaker 1: not by some sort of a conspiracy or by some

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Speaker 1: sort of a you know, alien shenanigans. But just because

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Speaker 1: things don't last that long, that's a it's an alien

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Speaker 1: concept from too many of our again, too many of

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Speaker 1: our creative visions of of what the future in the past,

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Speaker 1: maybe exactly so we think, well, you know, there are

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Speaker 1: ruins of civilizations from thousands of years ago, but that's

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Speaker 1: thousands of years ago. That's nothing in geological time. The

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Speaker 1: surface of the I mean, look a look at what

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Speaker 1: a map of the land formations on Earth just you know,

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Speaker 1: sixty million years ago looked like it's like, you know,

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Speaker 1: the the surface of the Earth is not fixed and constant.

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Speaker 1: This is a geologically active planet. So would there be

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Speaker 1: ruins all around us with evidence of a civilization from

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Speaker 1: hundreds of millions of years ago just be totally obvious?

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Speaker 1: I think I probably by the answer that the authors

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Speaker 1: give here, which is that no, it would probably not

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Speaker 1: be totally obvious. In fact, it might be incredibly difficult

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Speaker 1: to find evidence of at all. Uh. And so one

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Speaker 1: of the the interesting points the authors make here is

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Speaker 1: that the the exposed land surface of Earth, of course,

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Speaker 1: is geologically very young on average. They cite evidence from

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Speaker 1: a study by Mattman at All in two thousand nine

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Speaker 1: that the oldest large patch of land surface on Earth

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Speaker 1: is probably in the Negev Desert, and that's only about

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Speaker 1: one point eight million years old. At one point eight

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Speaker 1: million years, I mean, compared to the history of civilization,

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Speaker 1: is a long time. But that's again, it's like nothing

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Speaker 1: in geological times, a tiny fraction of of Earth history.

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Speaker 1: So if we wanted to find remnants of a civilization

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Speaker 1: from say, hundreds of millions of years ago, you probably

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Speaker 1: would not find that on the surface of the Earth.

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Speaker 1: You'd have to look for it in in exposed geological

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Speaker 1: strata from from previous eras. And even then you can't

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Speaker 1: just count on the fact that you would be finding

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Speaker 1: fossils of that civilization all over the place. Yeah, exactly.

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Speaker 1: That they that they had done something we you've discussed

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Speaker 1: in the show before, which is of course that the

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Speaker 1: fossil record is inherently incomplete, because fossilization only occurs when

429
00:24:16,760 --> 00:24:21,000
Speaker 1: conditions are just right. Um. They point out that that

430
00:24:21,119 --> 00:24:24,400
Speaker 1: of all the dinosaurs that ever lived, and there were

431
00:24:24,440 --> 00:24:27,520
Speaker 1: a ton of you know, uh, you know, they're the

432
00:24:27,880 --> 00:24:31,640
Speaker 1: era of the dinosaurs taken as as one gigantic, gigantic

433
00:24:31,640 --> 00:24:36,119
Speaker 1: monolith just dwarfs anything that that that that humanity has

434
00:24:36,160 --> 00:24:38,720
Speaker 1: ever occupied. Uh. You know, it is a it is

435
00:24:38,760 --> 00:24:42,159
Speaker 1: a cathedral, and and we're we're not even like a

436
00:24:42,240 --> 00:24:47,640
Speaker 1: child's dollhouse, uh sort of situation here. Um. So, uh,

437
00:24:47,680 --> 00:24:49,920
Speaker 1: you know, out of out of all of those dinosaurs

438
00:24:49,960 --> 00:24:52,000
Speaker 1: that ever lived, there are only a few thousand near

439
00:24:52,080 --> 00:24:55,160
Speaker 1: complete specimens. And so the authors here contend that given

440
00:24:55,200 --> 00:24:58,439
Speaker 1: the rarity of fossilization, a species is short lived, as

441
00:24:58,480 --> 00:25:01,760
Speaker 1: Homo sapiens m not make it into the fossil record

442
00:25:01,840 --> 00:25:05,160
Speaker 1: at all. And of course, for fossilization to mean anything

443
00:25:05,400 --> 00:25:09,359
Speaker 1: to us or to you know, anybody who's doing and doing,

444
00:25:09,400 --> 00:25:11,479
Speaker 1: you know, some sort of an investigation of a planet

445
00:25:11,560 --> 00:25:15,439
Speaker 1: or our planet, those fossilizations would have to survive and

446
00:25:15,480 --> 00:25:17,920
Speaker 1: then they would have to be found. Yeah, exactly. And

447
00:25:18,160 --> 00:25:20,800
Speaker 1: so again this might be pushing against your intuition. You

448
00:25:20,840 --> 00:25:23,000
Speaker 1: would say, like, wait a minute, there's there's there's there's

449
00:25:23,000 --> 00:25:25,720
Speaker 1: signs of human life all over the surface of Earth.

450
00:25:25,760 --> 00:25:28,320
Speaker 1: And and we have you know, at least a few thousand,

451
00:25:28,680 --> 00:25:32,480
Speaker 1: uh complete dinosaur fossils, enough to have museums of Natural

452
00:25:32,520 --> 00:25:35,800
Speaker 1: history with dinosaur fossils in places all over the world. Uh,

453
00:25:35,960 --> 00:25:39,680
Speaker 1: surely you'd expect more. But dinosaurs existed for almost two

454
00:25:39,800 --> 00:25:45,000
Speaker 1: hundred million years. Human civilization again is like it's a

455
00:25:45,040 --> 00:25:49,240
Speaker 1: few thousand years at this point. Yeah. So the problem

456
00:25:49,280 --> 00:25:52,600
Speaker 1: here is like we have trouble comparing the odds because

457
00:25:53,119 --> 00:25:57,040
Speaker 1: you're not realizing how many millions of times more the

458
00:25:57,160 --> 00:26:02,640
Speaker 1: dinosaur bodies got to roll the dice than our cors would. Yeah. Absolutely.

459
00:26:03,119 --> 00:26:05,520
Speaker 1: Another thing they touch on is that is the example

460
00:26:05,560 --> 00:26:08,840
Speaker 1: of technology. Uh, and they point out how rarely complex

461
00:26:08,880 --> 00:26:12,359
Speaker 1: early examples of human technology are ever found. So if

462
00:26:12,359 --> 00:26:15,160
Speaker 1: you're thinking, well, surely we would find one of these

463
00:26:15,160 --> 00:26:18,120
Speaker 1: factories or something that was made by one of these

464
00:26:18,160 --> 00:26:23,520
Speaker 1: factories that a previous civilization might have had, well not necessarily. Yeah, sure,

465
00:26:23,680 --> 00:26:26,840
Speaker 1: surely my rice cooker would be found hundreds of millions

466
00:26:26,840 --> 00:26:29,399
Speaker 1: of years in the future. But yeah, that that they

467
00:26:29,640 --> 00:26:33,199
Speaker 1: mentioned several reasons why that's maybe not as clear as

468
00:26:33,280 --> 00:26:37,359
Speaker 1: you might assume. So they say urbanization that currently represents

469
00:26:37,440 --> 00:26:40,720
Speaker 1: less than one percent of the Earth's surface, So that's

470
00:26:40,720 --> 00:26:44,280
Speaker 1: a limitation on the deposition side of creating a fossil

471
00:26:44,320 --> 00:26:47,639
Speaker 1: record of our current civilization. Only small parts of Earth's

472
00:26:47,640 --> 00:26:51,520
Speaker 1: surface are actually inhabited by humans. That that sounds counterintuitive,

473
00:26:51,560 --> 00:26:55,320
Speaker 1: but it's true. And then they point out that quote,

474
00:26:55,359 --> 00:26:59,600
Speaker 1: exposed sections and drilling sites for pre quaternary surfaces are

475
00:26:59,720 --> 00:27:03,720
Speaker 1: order of magnitude less as fractions of the original surface.

476
00:27:04,080 --> 00:27:07,879
Speaker 1: So human civilization currently only feels a small portion of

477
00:27:07,920 --> 00:27:13,280
Speaker 1: Earth's surface right now, and we only access tiny fractions

478
00:27:13,320 --> 00:27:16,680
Speaker 1: of Earth's previous surface through through various kinds of drilling,

479
00:27:16,720 --> 00:27:20,560
Speaker 1: and you know, access through exposure to rock strata. So

480
00:27:20,600 --> 00:27:25,119
Speaker 1: there's just like extreme selection filters on both sides, on

481
00:27:25,160 --> 00:27:28,480
Speaker 1: the deposition and on the excavation side. Yeah, it would

482
00:27:28,480 --> 00:27:31,919
Speaker 1: be kind of like even if you knew somehow, with

483
00:27:32,040 --> 00:27:35,800
Speaker 1: some certainty that there was that there was a technological

484
00:27:35,800 --> 00:27:38,879
Speaker 1: civilization during this time and in the ancient ancient past,

485
00:27:39,359 --> 00:27:41,439
Speaker 1: uh yeah, you would. You would have to you have

486
00:27:41,480 --> 00:27:43,800
Speaker 1: to really know exactly where to drill down to hit them.

487
00:27:44,040 --> 00:27:46,800
Speaker 1: You couldn't just expect to randomly do it unless you

488
00:27:46,840 --> 00:27:52,600
Speaker 1: did a lot of drilling and digging and excavation. But

489
00:27:52,600 --> 00:27:55,159
Speaker 1: but but so what we've been talking about here is

490
00:27:56,040 --> 00:27:59,400
Speaker 1: challenging the the intuition that you would just be finding

491
00:28:00,000 --> 00:28:04,680
Speaker 1: physical fossil remnants and artifacts of this civilization from hundreds

492
00:28:04,680 --> 00:28:07,000
Speaker 1: of millions of years ago all over the place, and

493
00:28:07,320 --> 00:28:09,240
Speaker 1: I think they do a very good job of knocking

494
00:28:09,320 --> 00:28:12,200
Speaker 1: that down. But of course it is not hopeless, because

495
00:28:12,200 --> 00:28:14,520
Speaker 1: they say, while our chance of finding the physical remains

496
00:28:14,560 --> 00:28:18,720
Speaker 1: of a hypothetical Silarian civilization might be very low, there

497
00:28:18,720 --> 00:28:21,600
Speaker 1: would be other traces of the existence of that civilization

498
00:28:21,680 --> 00:28:25,320
Speaker 1: that would be preserved in the geologic record, and you

499
00:28:25,320 --> 00:28:29,480
Speaker 1: you would have a very good chance of finding those traces. Yeah,

500
00:28:29,680 --> 00:28:31,080
Speaker 1: and that's that's what most of the rest of the

501
00:28:31,080 --> 00:28:33,080
Speaker 1: paper deals with. I do want to point out one

502
00:28:33,080 --> 00:28:34,879
Speaker 1: other thing that they bring up in passing that I

503
00:28:34,880 --> 00:28:37,920
Speaker 1: thought was interesting. They point out that that you could

504
00:28:37,920 --> 00:28:41,160
Speaker 1: certainly make an argument for or against the evolution of

505
00:28:41,160 --> 00:28:44,200
Speaker 1: intelligent life in a world based on the probable evolution

506
00:28:44,240 --> 00:28:47,600
Speaker 1: of species that are in the fossil record, but that

507
00:28:47,640 --> 00:28:54,040
Speaker 1: they would be focusing on physiochemical tracers for previous industrial civilization.

508
00:28:54,120 --> 00:28:55,840
Speaker 1: So I hadn't really thought about this, but like the

509
00:28:55,880 --> 00:29:00,400
Speaker 1: idea of like looking at say, dinosaur um fall souls

510
00:29:00,560 --> 00:29:03,600
Speaker 1: and saying, well, we don't have evidence that they evolved

511
00:29:03,600 --> 00:29:07,400
Speaker 1: in it into an intelligent technological species, but if we

512
00:29:07,520 --> 00:29:10,120
Speaker 1: but we can make an argument based on this fossil

513
00:29:10,160 --> 00:29:12,640
Speaker 1: and this fossil fossil that they were headed in that direction.

514
00:29:13,000 --> 00:29:14,720
Speaker 1: I feel like even that's the kind of thing that

515
00:29:14,760 --> 00:29:18,120
Speaker 1: probably wouldn't be quite as clear as your intuition might

516
00:29:18,240 --> 00:29:21,000
Speaker 1: lead you to assign them, because I mean, like intelligence

517
00:29:21,040 --> 00:29:26,360
Speaker 1: in mammals arose very rapidly in geologic time. Yeah, so

518
00:29:26,400 --> 00:29:30,200
Speaker 1: again it reached this situation where the fossil record could

519
00:29:30,200 --> 00:29:33,720
Speaker 1: just be missing that snapshot entirely. So this all leads

520
00:29:33,720 --> 00:29:36,000
Speaker 1: you next to the next major question. Given the limits

521
00:29:36,040 --> 00:29:38,960
Speaker 1: of what we can detect in the geochemical record, what

522
00:29:39,080 --> 00:29:41,840
Speaker 1: exactly could we look for on a planet to see

523
00:29:41,880 --> 00:29:45,880
Speaker 1: if an industrial society ever existed there? And yeah, that's

524
00:29:45,920 --> 00:29:47,960
Speaker 1: what the bulk of the paper focuses on. So in

525
00:29:47,960 --> 00:29:52,040
Speaker 1: the case of Earth, if an organized, intelligent society evolved

526
00:29:52,120 --> 00:29:56,880
Speaker 1: during the pre Quaternary time but they didn't reach the

527
00:29:56,960 --> 00:29:59,680
Speaker 1: level of an industrial society, there simply would be no

528
00:30:00,040 --> 00:30:02,320
Speaker 1: heard off them as far as this paper is concerned.

529
00:30:02,840 --> 00:30:06,959
Speaker 1: Right there, they're looking for the kinds of chemical material

530
00:30:07,080 --> 00:30:09,760
Speaker 1: and climate type changes that would leave a trace in

531
00:30:09,800 --> 00:30:12,760
Speaker 1: the geologic record, and that would primarily be a function

532
00:30:13,120 --> 00:30:18,680
Speaker 1: of of industry, basically of energy production, of of material

533
00:30:18,760 --> 00:30:22,880
Speaker 1: working things like metals and plastics, and the UH and

534
00:30:22,960 --> 00:30:26,960
Speaker 1: the methods of harnessing energy for industrial use. I was

535
00:30:27,000 --> 00:30:32,800
Speaker 1: reminded of our episodes on fire technology because if listeners

536
00:30:32,840 --> 00:30:35,520
Speaker 1: may remember, we discussed well, could something that evolved in

537
00:30:35,560 --> 00:30:38,160
Speaker 1: the water or or on a water world, could they

538
00:30:38,200 --> 00:30:41,560
Speaker 1: ever really get any kind of advanced technology going if

539
00:30:41,560 --> 00:30:44,360
Speaker 1: they didn't have access to the surface. And that seems

540
00:30:44,400 --> 00:30:46,080
Speaker 1: to be a factor here as well, as they're only

541
00:30:46,080 --> 00:30:49,400
Speaker 1: looking at the period during which something could have evolved

542
00:30:49,440 --> 00:30:53,160
Speaker 1: on land. Yeah, so you could maybe have advanced intelligence

543
00:30:53,160 --> 00:30:56,120
Speaker 1: in the water. But it's maybe this is just a

544
00:30:56,200 --> 00:30:58,200
Speaker 1: lack of imagination on our party. You know, you always

545
00:30:58,240 --> 00:31:00,680
Speaker 1: need to be aware of the limitation of your vision.

546
00:31:00,800 --> 00:31:04,440
Speaker 1: But it does seem hard to imagine advanced technology under

547
00:31:04,440 --> 00:31:07,240
Speaker 1: the water, because like, if you don't have fire, you

548
00:31:07,280 --> 00:31:10,080
Speaker 1: can't do metal working, or metal working is very difficult.

549
00:31:10,160 --> 00:31:11,800
Speaker 1: I don't I don't know. It just seems harder to

550
00:31:11,880 --> 00:31:15,120
Speaker 1: imagine how technology like we understand it could come about

551
00:31:15,200 --> 00:31:18,440
Speaker 1: in the water. But again, you know, limits of our vision. Yeah,

552
00:31:18,520 --> 00:31:20,440
Speaker 1: so they say, quote, the focus is thus on the

553
00:31:20,480 --> 00:31:23,360
Speaker 1: period between the emergence of complex life on land in

554
00:31:23,600 --> 00:31:27,160
Speaker 1: the Devonian four million years ago in the Paleozoic era

555
00:31:27,600 --> 00:31:30,760
Speaker 1: and the mid apply a scene. Uh, and that's around

556
00:31:30,760 --> 00:31:33,760
Speaker 1: four million years ago. Yeah, because if it was much

557
00:31:33,840 --> 00:31:36,760
Speaker 1: more recent, you you'd probably get into the area where

558
00:31:36,800 --> 00:31:39,240
Speaker 1: you'd start to expect to actually see those kinds of

559
00:31:39,720 --> 00:31:42,840
Speaker 1: remnants and artifacts that that we were talking about. Right,

560
00:31:43,520 --> 00:31:45,960
Speaker 1: So they get into the discussion of what we might

561
00:31:46,080 --> 00:31:49,080
Speaker 1: look for, and they have it nicely divided up. The

562
00:31:49,080 --> 00:31:52,479
Speaker 1: first one is, uh, well, they basically have two broad

563
00:31:52,600 --> 00:31:56,880
Speaker 1: categories and then some some details on that category. The

564
00:31:56,880 --> 00:31:59,960
Speaker 1: first big one though, would be looking at the geological

565
00:32:00,040 --> 00:32:02,920
Speaker 1: footprint of the anthroposcene. So, as we've discussed in the

566
00:32:02,960 --> 00:32:05,040
Speaker 1: show before, there's an argument to be made that the

567
00:32:05,040 --> 00:32:07,920
Speaker 1: impact of human civilization on the environment and the geologic

568
00:32:08,000 --> 00:32:13,200
Speaker 1: record constitutes its own geologic era, the Anthropocene. So not

569
00:32:13,240 --> 00:32:15,840
Speaker 1: all the changes would be recognizable millions of years later,

570
00:32:15,880 --> 00:32:19,200
Speaker 1: but some would be. Right. So, human activity at this

571
00:32:19,320 --> 00:32:23,720
Speaker 1: point is is large scale enough that we are making

572
00:32:23,880 --> 00:32:28,440
Speaker 1: changes to the earth that that are that are widespread

573
00:32:28,640 --> 00:32:31,400
Speaker 1: or you could even say global, and I was gonna

574
00:32:31,400 --> 00:32:34,040
Speaker 1: say permanent, not permanent, but extremely long lived. You know,

575
00:32:34,120 --> 00:32:36,840
Speaker 1: going way into the future, you will be able to

576
00:32:36,920 --> 00:32:40,440
Speaker 1: find signs in the rocks and the ice and the settiment,

577
00:32:40,480 --> 00:32:42,680
Speaker 1: you know, the things on Earth that persists over long

578
00:32:42,720 --> 00:32:45,800
Speaker 1: periods of time that will leave records of what we

579
00:32:45,840 --> 00:32:48,560
Speaker 1: did to the Earth in just the past three years

580
00:32:48,640 --> 00:32:52,600
Speaker 1: or so. Right and uh, and as we've probably mentioned before,

581
00:32:52,720 --> 00:32:57,760
Speaker 1: the anthroposcene is not a an official geological era, as

582
00:32:57,840 --> 00:33:00,400
Speaker 1: much as any of these things can be, you know, officials.

583
00:33:00,600 --> 00:33:02,680
Speaker 1: It seems like when you're talking about geologic terms, it's

584
00:33:02,680 --> 00:33:06,280
Speaker 1: even more ridiculous. We can consider such a small part

585
00:33:06,320 --> 00:33:09,800
Speaker 1: of geologic history that we occupy, but there's a lot

586
00:33:09,800 --> 00:33:12,480
Speaker 1: of compelling evidence for it, and you often see it discussed,

587
00:33:12,560 --> 00:33:16,280
Speaker 1: especially when we're talking about the changes that that humans

588
00:33:16,280 --> 00:33:18,640
Speaker 1: have made to the planet and arem still making to

589
00:33:18,680 --> 00:33:21,160
Speaker 1: the planet, and how they may show up in the

590
00:33:21,160 --> 00:33:24,360
Speaker 1: geologic record. And just to be super clear, the majority

591
00:33:24,400 --> 00:33:26,680
Speaker 1: of the changes we're talking about of this kind would

592
00:33:26,680 --> 00:33:30,400
Speaker 1: not be changes like physical alterations of the Earth's surface.

593
00:33:30,600 --> 00:33:33,720
Speaker 1: We're not talking about like records of people digging holes

594
00:33:33,800 --> 00:33:37,600
Speaker 1: and building stuff. We're talking about records of like changes

595
00:33:37,720 --> 00:33:42,280
Speaker 1: to the to the level of different carbon isotopes in

596
00:33:42,280 --> 00:33:46,080
Speaker 1: in geological strata and things like that. Right now, they

597
00:33:46,120 --> 00:33:48,200
Speaker 1: also hit upon something that that I thought was really

598
00:33:48,200 --> 00:33:51,600
Speaker 1: interesting in in in a way almost almost encouraging, uh,

599
00:33:51,640 --> 00:33:55,000
Speaker 1: the sustainability paradox. So the idea here is that, of

600
00:33:55,040 --> 00:34:00,200
Speaker 1: course the longer human civilization lasts, especially technological civilization, the

601
00:34:00,320 --> 00:34:04,400
Speaker 1: greater the geologic signal of its impact. Again, that that

602
00:34:04,640 --> 00:34:08,120
Speaker 1: lasting those lasting signs in the environment, not the faces

603
00:34:08,160 --> 00:34:13,120
Speaker 1: they carved into the mountains, but impacts again on their

604
00:34:13,160 --> 00:34:18,200
Speaker 1: their geochemical in nature. Um, so that signal increases. But

605
00:34:18,400 --> 00:34:22,919
Speaker 1: the longer human civilization lasts, the more sustainable it must

606
00:34:23,000 --> 00:34:26,000
Speaker 1: become in order to survive. And this is of course

607
00:34:26,040 --> 00:34:29,160
Speaker 1: the reality we're living in right now. If a civilization

608
00:34:29,239 --> 00:34:33,040
Speaker 1: survives this test and becomes more sustainable, then that signal

609
00:34:33,440 --> 00:34:36,200
Speaker 1: grows weaker. Right. So it's almost like the strength of

610
00:34:36,200 --> 00:34:40,000
Speaker 1: the signal left for future people to discover is directly

611
00:34:40,080 --> 00:34:45,120
Speaker 1: proportional to how suicidal that civilization is, right Like, the

612
00:34:45,560 --> 00:34:48,920
Speaker 1: more it is just burning through fossil fuel resources and

613
00:34:48,960 --> 00:34:51,480
Speaker 1: the rate of that, the stronger the signal will be.

614
00:34:51,640 --> 00:34:55,200
Speaker 1: And so a civilization at some point, they say, well,

615
00:34:55,239 --> 00:34:58,520
Speaker 1: will naturally tend to attenuate for a couple of reasons.

616
00:34:58,560 --> 00:35:01,759
Speaker 1: Either it really says it can't keep going at that rate,

617
00:35:01,880 --> 00:35:04,799
Speaker 1: or it's going to cause climate damage to itself, so

618
00:35:04,880 --> 00:35:09,080
Speaker 1: it will naturally switch to more sustainable uh energy sources

619
00:35:09,120 --> 00:35:11,600
Speaker 1: that are harder to detect in the future, or it

620
00:35:11,680 --> 00:35:14,040
Speaker 1: of course does so much damage to itself that it's

621
00:35:14,080 --> 00:35:18,439
Speaker 1: signal naturally is reduced, right right. So, so basically coming

622
00:35:18,440 --> 00:35:19,840
Speaker 1: back to what you said earlier, it's not just that

623
00:35:19,880 --> 00:35:21,880
Speaker 1: there there's gonna be a sign. There's gonna be the

624
00:35:21,920 --> 00:35:25,440
Speaker 1: signal uh, this footprint of a civilization uh in the

625
00:35:25,520 --> 00:35:28,479
Speaker 1: in the you know, the geochemical record. It's it's also

626
00:35:28,560 --> 00:35:30,320
Speaker 1: that it may just be very short, it may be

627
00:35:30,640 --> 00:35:33,200
Speaker 1: a little it's not going to be this Uh. It's

628
00:35:33,200 --> 00:35:34,920
Speaker 1: not gonna be a symphony. It's going to maybe be

629
00:35:34,960 --> 00:35:38,399
Speaker 1: a note or two. So basically the idea being that

630
00:35:38,400 --> 00:35:43,560
Speaker 1: that that the real strong, much stronger argument for aliens

631
00:35:43,560 --> 00:35:45,920
Speaker 1: existing and having some sort of role or some sort

632
00:35:45,920 --> 00:35:48,680
Speaker 1: of advanced technology having some sort of role on Earth

633
00:35:48,760 --> 00:35:51,960
Speaker 1: and they in the ancient history would not be look

634
00:35:52,000 --> 00:35:54,759
Speaker 1: at the pyramids, I think aliens did this, or I

635
00:35:54,800 --> 00:35:58,000
Speaker 1: think you know, ancient scientists did this. It would be

636
00:35:58,040 --> 00:36:01,360
Speaker 1: pointing at say a blip and uh or an increase

637
00:36:01,400 --> 00:36:04,960
Speaker 1: in global temperatures during a certain period of time and saying,

638
00:36:05,080 --> 00:36:07,600
Speaker 1: I think the aliens did this? Or I think the

639
00:36:07,640 --> 00:36:11,120
Speaker 1: advanced technology and question did this? I mean, even then,

640
00:36:11,200 --> 00:36:13,759
Speaker 1: I think that would be a very speculative and and

641
00:36:13,840 --> 00:36:16,120
Speaker 1: difficult to prove hypothesis. It would be kind of just

642
00:36:16,160 --> 00:36:21,719
Speaker 1: like unfalsifiable speculation, but that that would perhaps be the

643
00:36:21,920 --> 00:36:25,480
Speaker 1: more likely type of signal you would find if there

644
00:36:25,480 --> 00:36:34,399
Speaker 1: had been alien intervention. Then you know, specific artifacts than

645
00:36:36,280 --> 00:36:38,000
Speaker 1: al right, well, let's get into some of the specifics

646
00:36:38,000 --> 00:36:40,839
Speaker 1: of the footprint that the authors lay out here. The

647
00:36:40,840 --> 00:36:45,040
Speaker 1: first one is a stable isotope anomalies of carbon, oxygen, hydrogen,

648
00:36:45,080 --> 00:36:47,719
Speaker 1: and nitrogen. And this is one of the big ones.

649
00:36:47,719 --> 00:36:51,839
Speaker 1: An estimated point five trillion tons of fossil carbon via

650
00:36:51,880 --> 00:36:54,680
Speaker 1: the burning of fossil fuels and warming of the planet

651
00:36:55,080 --> 00:36:58,600
Speaker 1: um they quote, we we expect this temperature rise to

652
00:36:58,640 --> 00:37:04,160
Speaker 1: be detectable and so FA ocean uh carbonates notably forminifera.

653
00:37:04,360 --> 00:37:06,680
Speaker 1: This is a single celled organism with a with a

654
00:37:06,960 --> 00:37:12,640
Speaker 1: with a chalky shell. UM. Organic biomarkers cave records, stuches

655
00:37:12,640 --> 00:37:18,800
Speaker 1: such as stalactites, lake ostracods. These are minute aquatic crustaceans

656
00:37:19,239 --> 00:37:22,480
Speaker 1: and high latitude ice cores, though only the first two

657
00:37:22,560 --> 00:37:26,320
Speaker 1: of these will be retrievable in the time scales considered

658
00:37:26,360 --> 00:37:29,960
Speaker 1: here un Right, So this thing about the the isotope

659
00:37:30,000 --> 00:37:33,400
Speaker 1: anomalies of of carbon and these other elements is very interesting.

660
00:37:33,440 --> 00:37:35,840
Speaker 1: So they say, you know, there are natural distributions that

661
00:37:35,880 --> 00:37:38,840
Speaker 1: you would find records of in the different isotopes of

662
00:37:38,880 --> 00:37:42,279
Speaker 1: carbon that are that are moving around in Earth's atmosphere.

663
00:37:42,840 --> 00:37:47,400
Speaker 1: But when people suddenly start pulling huge amounts of fossil carbon,

664
00:37:47,520 --> 00:37:51,200
Speaker 1: carbon of a biological origin out of the ground and

665
00:37:51,280 --> 00:37:55,160
Speaker 1: burning it, you suddenly start throwing those isotopes out of whack,

666
00:37:55,560 --> 00:37:58,279
Speaker 1: and that will be something that will leave records for

667
00:37:58,400 --> 00:38:00,840
Speaker 1: millions of years to come. So you can look in

668
00:38:00,920 --> 00:38:03,920
Speaker 1: the geological records, you know, the record of of strata

669
00:38:03,960 --> 00:38:07,120
Speaker 1: from previous eras, and say hunh. For some reason, in

670
00:38:07,120 --> 00:38:10,960
Speaker 1: this one period deep in history, suddenly the carbon isotopes

671
00:38:11,040 --> 00:38:13,920
Speaker 1: got way out of whack, as if suddenly a bunch

672
00:38:14,040 --> 00:38:17,399
Speaker 1: of fossil carbon like coal or oil or whatever had

673
00:38:17,400 --> 00:38:21,080
Speaker 1: been burned at a at a hideous rate into the atmosphere. Right.

674
00:38:21,160 --> 00:38:23,439
Speaker 1: And so you know, looking at our our time now

675
00:38:23,960 --> 00:38:26,719
Speaker 1: of of of modern human civilization, you know this that

676
00:38:26,920 --> 00:38:29,359
Speaker 1: we have this fossil fuel consumption and we have the

677
00:38:29,400 --> 00:38:33,040
Speaker 1: invention of the haber Bosch process and the large scale

678
00:38:33,120 --> 00:38:37,640
Speaker 1: use of of nitrogenous fertilizers and agriculture, which will also

679
00:38:37,719 --> 00:38:42,359
Speaker 1: heavily impact the planet's nitrogen cycling. Yeah, the haber Bosch process, Yeah,

680
00:38:42,360 --> 00:38:45,200
Speaker 1: as part of the changes in the nitrogen cycle that

681
00:38:45,200 --> 00:38:48,839
Speaker 1: have come about as a result of of industrial civilization.

682
00:38:48,880 --> 00:38:52,840
Speaker 1: As well. They also touched on sediment to logical records.

683
00:38:53,320 --> 00:38:56,600
Speaker 1: The key causes here would be major soil erosion brought

684
00:38:56,640 --> 00:39:02,399
Speaker 1: on by agriculture, but also by agriculture lated deforestation. Um. Now,

685
00:39:02,400 --> 00:39:05,560
Speaker 1: this would be partially mitigated by dams, they point out,

686
00:39:05,800 --> 00:39:09,400
Speaker 1: but erosion is also heightened by climate changes and thawing

687
00:39:09,480 --> 00:39:14,520
Speaker 1: perma frost. Also sediment content changes due to just industrialization

688
00:39:14,560 --> 00:39:17,680
Speaker 1: in general. Uh. Now here's a There's another big one

689
00:39:17,680 --> 00:39:22,840
Speaker 1: that I think will be pretty obvious. Faunnel radiation and extinctions. Um. Basically,

690
00:39:22,880 --> 00:39:25,560
Speaker 1: humans have brought about many extinctions already, and we're living

691
00:39:25,600 --> 00:39:29,000
Speaker 1: in the midst of an extinction event. Uh. This will

692
00:39:29,040 --> 00:39:32,680
Speaker 1: likely register in the fossil record. Yeah. Now, of course,

693
00:39:33,080 --> 00:39:37,360
Speaker 1: previous major extinction events have usually been chalked up to

694
00:39:37,719 --> 00:39:41,760
Speaker 1: two natural things like uh, oh, we can track massive

695
00:39:41,840 --> 00:39:44,920
Speaker 1: vulcanisms as the cause of this one, or say a

696
00:39:45,719 --> 00:39:49,640
Speaker 1: large space impact like the Katie extinction event. But there

697
00:39:49,640 --> 00:39:52,640
Speaker 1: are other extinction events in Earth's history where the cause

698
00:39:52,800 --> 00:39:55,880
Speaker 1: is not totally clear. You know, there are some speculations,

699
00:39:55,920 --> 00:39:58,360
Speaker 1: but we don't know exactly why. Suddenly it seemed like

700
00:39:58,360 --> 00:40:01,680
Speaker 1: there was a great reduction in marine biodiversity at this

701
00:40:01,760 --> 00:40:04,399
Speaker 1: point in history. All right. The next area is non

702
00:40:04,560 --> 00:40:08,759
Speaker 1: naturally occurring synthetics, So non naturally occurring chemicals generated by

703
00:40:08,800 --> 00:40:13,960
Speaker 1: industrial activity that persists in the environment. Things persistent organic pollutants,

704
00:40:14,280 --> 00:40:18,359
Speaker 1: chlorofluoral carbons, in related compounds. And they also point out

705
00:40:18,400 --> 00:40:23,080
Speaker 1: that steroids, leaf waxes, alkanones, and lipids can be preserved

706
00:40:23,080 --> 00:40:25,960
Speaker 1: in sediment for many millions of years. Now, that one

707
00:40:26,040 --> 00:40:29,439
Speaker 1: naturally makes me think of King plastic baby. Yeah, yeah,

708
00:40:29,440 --> 00:40:32,160
Speaker 1: And that's that's the next thing that they mentioned. And

709
00:40:32,200 --> 00:40:35,719
Speaker 1: this one's you know, this one's disheartening but obvious. We've

710
00:40:35,719 --> 00:40:39,840
Speaker 1: created tons of plastics, tons upon tons upon tons of plastics,

711
00:40:39,920 --> 00:40:43,360
Speaker 1: and they sadly persist not only in heaps and floating masses,

712
00:40:43,400 --> 00:40:48,200
Speaker 1: but inside the bodies of organisms, including ourselves, uh so quote.

713
00:40:48,200 --> 00:40:53,239
Speaker 1: The potential for very long term persistence and detectability is high. Now.

714
00:40:53,280 --> 00:40:55,279
Speaker 1: One of the things they point out about plastic that's

715
00:40:55,320 --> 00:40:58,960
Speaker 1: interesting is that plastics may well proved to be a

716
00:40:59,120 --> 00:41:02,759
Speaker 1: very long term signature of human civilization and the geologic

717
00:41:02,840 --> 00:41:05,520
Speaker 1: record for you know, millions and millions of years to come.

718
00:41:05,600 --> 00:41:08,080
Speaker 1: But the development of plastic is also something they would

719
00:41:08,080 --> 00:41:10,359
Speaker 1: class under the I don't remember the umbrella term they

720
00:41:10,400 --> 00:41:14,120
Speaker 1: use for this, but sort of chemical contingencies. A technological

721
00:41:14,160 --> 00:41:17,880
Speaker 1: civilization does not have to use plastics. Plastics are just

722
00:41:18,160 --> 00:41:21,920
Speaker 1: something that humans happen to use. There are other things

723
00:41:21,960 --> 00:41:26,879
Speaker 1: that seem probably more universal, like almost any industrial civilization

724
00:41:27,440 --> 00:41:31,920
Speaker 1: you would expect to burn lots of fossil fuels, But plastics,

725
00:41:31,960 --> 00:41:34,520
Speaker 1: that's more of a question mark. Is that unusual that

726
00:41:34,600 --> 00:41:36,640
Speaker 1: we did it, or is that a very common thing

727
00:41:36,719 --> 00:41:40,040
Speaker 1: that the civilizations would do all right. The next area

728
00:41:40,080 --> 00:41:45,719
Speaker 1: that they highlight transuranic elements. These are elements having a

729
00:41:45,800 --> 00:41:50,359
Speaker 1: higher atomic number than uranium, which is ninety two. Most

730
00:41:50,480 --> 00:41:55,080
Speaker 1: radioactive isotopes created via nuclear energy or weaponry have long

731
00:41:55,239 --> 00:41:57,880
Speaker 1: half lives, but not long enough to be a factor

732
00:41:58,000 --> 00:42:00,239
Speaker 1: on the time scale that they're talking about here. But

733
00:42:00,280 --> 00:42:04,840
Speaker 1: the exceptions are plutonium to forty four and um curium

734
00:42:04,920 --> 00:42:08,080
Speaker 1: two forty seven. So plutonium has a half life of

735
00:42:08,360 --> 00:42:12,359
Speaker 1: eight point eight million years, and curium in this case

736
00:42:12,400 --> 00:42:15,080
Speaker 1: we're talking about a half life of fifteen million years.

737
00:42:15,120 --> 00:42:18,600
Speaker 1: So in sufficient quantities of disposal, these would these would

738
00:42:18,719 --> 00:42:23,360
Speaker 1: pop up. And plutonium has no known natural causes outside

739
00:42:23,360 --> 00:42:26,640
Speaker 1: of an actual supernova or something like that. This isotope

740
00:42:26,640 --> 00:42:29,759
Speaker 1: of plutonium. Yes, this particularly yea plutonium two forty four

741
00:42:29,880 --> 00:42:33,000
Speaker 1: so um. So, Yeah, if you found enough of this

742
00:42:33,440 --> 00:42:36,040
Speaker 1: uh in the geologic record, that would be a sign

743
00:42:36,160 --> 00:42:38,480
Speaker 1: that's that's something was at work, there was some sort

744
00:42:38,480 --> 00:42:44,640
Speaker 1: of technological atomic uh enterprise that was in place. Now,

745
00:42:44,680 --> 00:42:48,399
Speaker 1: I guess we've already mentioned earlier that the authors are

746
00:42:48,440 --> 00:42:51,840
Speaker 1: not going to claim that there was in fact a

747
00:42:51,680 --> 00:42:55,160
Speaker 1: a long lost civilization hundreds of millions of years ago.

748
00:42:55,560 --> 00:42:58,919
Speaker 1: But they do actually look at the geologic record to say,

749
00:42:59,560 --> 00:43:03,520
Speaker 1: are there anythings that that match these criteria we've been

750
00:43:03,560 --> 00:43:06,880
Speaker 1: looking at, And they do find some interesting partial matches

751
00:43:06,920 --> 00:43:09,200
Speaker 1: that have though of course nothing really comes close to

752
00:43:09,400 --> 00:43:12,520
Speaker 1: evidence that would be conclusive that there actually was a civilization,

753
00:43:12,600 --> 00:43:16,399
Speaker 1: but some of these matches raise interesting questions of their own. Yeah,

754
00:43:16,640 --> 00:43:18,680
Speaker 1: they don't look at everything, and they point out that

755
00:43:18,719 --> 00:43:21,200
Speaker 1: things like the kt extinction event. We know that that

756
00:43:21,280 --> 00:43:25,680
Speaker 1: was not an industrial accident or anything. Um and uh

757
00:43:25,680 --> 00:43:28,160
Speaker 1: and again they're not arguing that these are evidence of

758
00:43:28,200 --> 00:43:31,160
Speaker 1: past pre human industrial civilizations on Earth, but merely point

759
00:43:31,160 --> 00:43:34,520
Speaker 1: to them as the source of events we might look at. Yeah.

760
00:43:34,560 --> 00:43:37,200
Speaker 1: And I would say the biggest one that they focus

761
00:43:37,280 --> 00:43:39,680
Speaker 1: on in the paper is the event known as the

762
00:43:39,719 --> 00:43:44,080
Speaker 1: Paleocene Eocene Thermal Maximum or p e t M. Yeah.

763
00:43:44,120 --> 00:43:47,640
Speaker 1: This is an abrupt spike in carbon and oxygen isotopes

764
00:43:48,080 --> 00:43:53,279
Speaker 1: near the Paleocene Eocene transition fifty six million years ago,

765
00:43:53,360 --> 00:43:57,320
Speaker 1: resulting in a five to eight degree celsius global average

766
00:43:57,360 --> 00:44:01,160
Speaker 1: temperature rise. This is widely thought to be due to well,

767
00:44:01,160 --> 00:44:03,759
Speaker 1: I think they're there are different theories. One is that

768
00:44:03,800 --> 00:44:08,279
Speaker 1: it's volcanic activity. Um. But there have also been hypotheses

769
00:44:08,320 --> 00:44:10,440
Speaker 1: put forth that it could have been a common impact.

770
00:44:10,560 --> 00:44:14,480
Speaker 1: It could be due to burning pete, methane being released,

771
00:44:14,680 --> 00:44:17,480
Speaker 1: and a few other candidates. Um. It's also used as

772
00:44:17,480 --> 00:44:20,279
Speaker 1: a means of of understanding and kind of like kind

773
00:44:20,280 --> 00:44:23,399
Speaker 1: of modeling out the effects of climate change during our

774
00:44:23,440 --> 00:44:26,080
Speaker 1: own era. Yeah. And and one of the reasons this

775
00:44:26,120 --> 00:44:29,480
Speaker 1: one gets singled out is, uh, so it really looks like, Okay,

776
00:44:29,520 --> 00:44:33,440
Speaker 1: here we're seeing, for example, these carbon isotope signature changes

777
00:44:33,560 --> 00:44:37,680
Speaker 1: that would signal that huge amounts of biogenic carbon carbon

778
00:44:37,760 --> 00:44:40,279
Speaker 1: that originally came from life forms, like the stuff you

779
00:44:40,280 --> 00:44:43,280
Speaker 1: would find in fossil fuels, is being burned and released

780
00:44:43,280 --> 00:44:46,799
Speaker 1: into the atmosphere. Now, how would that happen if if

781
00:44:46,960 --> 00:44:49,399
Speaker 1: if it wasn't creatures from the Black Lagoon with leather

782
00:44:49,440 --> 00:44:52,960
Speaker 1: face masks digging up a bunch of fossil fuels and

783
00:44:52,960 --> 00:44:56,040
Speaker 1: burning them for their civilization. Well, no, you probably don't

784
00:44:56,080 --> 00:44:58,799
Speaker 1: need to jump to that conclusion because there are other

785
00:44:59,200 --> 00:45:01,640
Speaker 1: solutions on off for like, for example, there might have

786
00:45:01,719 --> 00:45:06,640
Speaker 1: somehow been lots of access of volcanic magma two beds

787
00:45:06,800 --> 00:45:11,240
Speaker 1: of fossil fuels. Maybe certain types of volcanic activity tended

788
00:45:11,280 --> 00:45:14,719
Speaker 1: to set a light to a lot of natural reserves

789
00:45:14,719 --> 00:45:17,359
Speaker 1: of fossil fuels and shale beds and things like that.

790
00:45:17,640 --> 00:45:20,680
Speaker 1: And this almost acted as if the Earth itself, we're

791
00:45:20,800 --> 00:45:23,319
Speaker 1: we're setting off an industrial revolution, but it was just

792
00:45:23,560 --> 00:45:28,680
Speaker 1: volcanoes interacting with with these reservoirs of carbon in the ground. Yeah,

793
00:45:28,800 --> 00:45:31,840
Speaker 1: all you need is geologic upheaval and volcanic activity and

794
00:45:31,880 --> 00:45:34,839
Speaker 1: again um our Our planet has A has A has

795
00:45:34,880 --> 00:45:39,360
Speaker 1: a very active geological life, so there's plenty of opportunity

796
00:45:39,400 --> 00:45:41,800
Speaker 1: for this sort of thing to potentially have taken place.

797
00:45:42,280 --> 00:45:43,680
Speaker 1: So it kind of comes back to a problem with

798
00:45:43,760 --> 00:45:46,160
Speaker 1: the signal here, the signal you would be looking for

799
00:45:46,239 --> 00:45:49,799
Speaker 1: in the geochemical record. In many cases, the very sort

800
00:45:49,800 --> 00:45:52,720
Speaker 1: of signal we're looking for, especially concerning carbon and warming,

801
00:45:53,000 --> 00:45:55,600
Speaker 1: could have also been caused by these naturally occurring causes,

802
00:45:55,640 --> 00:45:58,680
Speaker 1: and so strong signals might be coming from something else,

803
00:45:59,040 --> 00:46:01,680
Speaker 1: and more specific signals that we might look to just

804
00:46:01,760 --> 00:46:05,080
Speaker 1: might be too weak to to ever possibly observe or

805
00:46:05,120 --> 00:46:07,239
Speaker 1: to really make much out of. Oh yeah, this is

806
00:46:07,280 --> 00:46:09,840
Speaker 1: an interesting paradox they talk about in their conclusion of

807
00:46:09,880 --> 00:46:11,839
Speaker 1: all of the criteria they're able to come up with

808
00:46:11,880 --> 00:46:15,840
Speaker 1: in this framework for for looking for past industrial civilizations,

809
00:46:16,719 --> 00:46:20,440
Speaker 1: the stuff that you would expect any industrial civilization to

810
00:46:20,560 --> 00:46:25,279
Speaker 1: do also has other explanations, and so so it's not

811
00:46:25,360 --> 00:46:28,719
Speaker 1: conclusive that it was an industrial civilization that this would

812
00:46:28,719 --> 00:46:31,640
Speaker 1: be things like you know, the carbon stuff. Meanwhile, the

813
00:46:31,640 --> 00:46:36,040
Speaker 1: stuff that would be really strong evidence of an intelligent

814
00:46:36,080 --> 00:46:40,879
Speaker 1: civilization origin, that stuff that civilizations might not do. It's

815
00:46:40,920 --> 00:46:43,759
Speaker 1: more contingent things like plastics, and stuff. You know, you

816
00:46:43,800 --> 00:46:47,200
Speaker 1: could have a civilization without plastics. That's not a necessary

817
00:46:47,520 --> 00:46:51,400
Speaker 1: milestone in the in the progress of energy harnessing. And

818
00:46:51,480 --> 00:46:53,760
Speaker 1: maybe it's even the sort of thing. Uh an advance

819
00:46:53,760 --> 00:46:56,400
Speaker 1: civilization would move away from coming back to that the

820
00:46:56,440 --> 00:47:00,680
Speaker 1: sustainability paradox, when one could hope, I imagine. Now the

821
00:47:00,760 --> 00:47:04,160
Speaker 1: authors again, they're very clear about just how far you

822
00:47:04,200 --> 00:47:08,919
Speaker 1: should take this hypothesis, stating that quote, the Silurian hypothesis

823
00:47:09,000 --> 00:47:13,000
Speaker 1: cannot be regarded as likely merely because no other valid

824
00:47:13,080 --> 00:47:17,279
Speaker 1: idea presents itself. Uh So they admit that this this

825
00:47:17,320 --> 00:47:18,880
Speaker 1: sort of thing could easily get out of hand with

826
00:47:18,920 --> 00:47:21,920
Speaker 1: folks pointing to any sort of signal in the geochemical

827
00:47:22,000 --> 00:47:25,759
Speaker 1: record as being possible proof of pre human technological societies.

828
00:47:26,239 --> 00:47:29,160
Speaker 1: If you're doing that, you're really taking it and running

829
00:47:29,200 --> 00:47:31,799
Speaker 1: with it in the wrong direction. Yeah, I guess that's

830
00:47:31,800 --> 00:47:35,120
Speaker 1: one of the frustrating things about about interesting work of

831
00:47:35,160 --> 00:47:37,120
Speaker 1: this kind is so you can point out a lot

832
00:47:37,120 --> 00:47:42,440
Speaker 1: of the ways that it's difficult to rule out past civilizations.

833
00:47:42,440 --> 00:47:44,800
Speaker 1: But then for a lot of people who just want

834
00:47:44,880 --> 00:47:48,400
Speaker 1: to have a theory that changes everything, you know, for

835
00:47:48,400 --> 00:47:50,799
Speaker 1: a lot it's just like it's fun to believe that.

836
00:47:51,200 --> 00:47:53,040
Speaker 1: So a lot of people just want to believe it.

837
00:47:53,080 --> 00:47:55,120
Speaker 1: I want to believe, you know, that there was an

838
00:47:55,120 --> 00:47:58,560
Speaker 1: Atlantis mother civilization that birthed everything, or I want to

839
00:47:58,560 --> 00:48:01,719
Speaker 1: believe that there were alien on Earth before humans or

840
00:48:01,760 --> 00:48:04,600
Speaker 1: anything like that, because that would change everything, and it

841
00:48:04,600 --> 00:48:09,120
Speaker 1: feels so cool to believe it. Therefore becomes your default belief.

842
00:48:09,320 --> 00:48:12,120
Speaker 1: And so thus a paper that says, well, it's more

843
00:48:12,160 --> 00:48:14,799
Speaker 1: difficult to rule out that kind of thing than you

844
00:48:14,880 --> 00:48:19,400
Speaker 1: might think. Uh, some people can erroneously conclude that that

845
00:48:19,480 --> 00:48:21,799
Speaker 1: is in fact evidence for the thing they want to

846
00:48:21,800 --> 00:48:27,560
Speaker 1: believe because it feels cool. It's not positive evidence for it, yes, yeah, absolutely,

847
00:48:28,080 --> 00:48:30,600
Speaker 1: um yes, So so you know, they argue that that

848
00:48:30,680 --> 00:48:33,960
Speaker 1: we need to to further research, you know, the likely

849
00:48:34,040 --> 00:48:38,919
Speaker 1: signature left by our own um anthroposyne era, as well

850
00:48:38,960 --> 00:48:43,399
Speaker 1: as a deeper exploration of the elemental and um compositional

851
00:48:43,440 --> 00:48:48,160
Speaker 1: anomalies that we find in extant sediments. Basically, we look

852
00:48:48,160 --> 00:48:51,280
Speaker 1: at past events mainly with stuff like impacts in mind,

853
00:48:51,960 --> 00:48:55,440
Speaker 1: but perhaps the Silarian hypothesis needs to be at least

854
00:48:55,440 --> 00:48:58,520
Speaker 1: on the table as well. Not because again we think

855
00:48:58,560 --> 00:49:02,040
Speaker 1: it is, you know, actually a valid explanation for what

856
00:49:02,120 --> 00:49:05,719
Speaker 1: has happened. Um, you know, ultimately it's an outside possibility,

857
00:49:06,120 --> 00:49:08,800
Speaker 1: not a conclusion we should jump to, but perhaps it

858
00:49:08,840 --> 00:49:10,960
Speaker 1: should just be part of sort of the spectrum of

859
00:49:10,960 --> 00:49:14,840
Speaker 1: possibilities there. Again, not because we think it happened, but because,

860
00:49:15,400 --> 00:49:17,279
Speaker 1: uh it gives us a little more of a sort

861
00:49:17,320 --> 00:49:20,560
Speaker 1: of a robust spectrum and how to interpret these things.

862
00:49:20,920 --> 00:49:23,680
Speaker 1: And and then moving forward to you know, potentially considering

863
00:49:23,680 --> 00:49:26,839
Speaker 1: other worlds, looking at other planets like even Mars. Uh

864
00:49:26,880 --> 00:49:30,440
Speaker 1: it gives us one more tool, one more uh way

865
00:49:30,480 --> 00:49:33,760
Speaker 1: to look at the evidence. Yeah, exactly, they're not arguing

866
00:49:33,800 --> 00:49:37,239
Speaker 1: this because they think there was a civilization. It's that

867
00:49:37,360 --> 00:49:40,799
Speaker 1: we should consider these possibilities when looking at planets, even

868
00:49:40,800 --> 00:49:43,440
Speaker 1: including our own, and know what we would look for

869
00:49:43,600 --> 00:49:46,520
Speaker 1: if we wanted to consider that possibility, right, Yeah, because

870
00:49:46,560 --> 00:49:50,960
Speaker 1: ultimately this is not a supernatural explanation. This is ultimately,

871
00:49:51,400 --> 00:49:56,200
Speaker 1: you know, a natural hypothesis. But but it is admittedly

872
00:49:56,239 --> 00:49:59,040
Speaker 1: an outside possibility. Now, of course we're here talking about

873
00:49:59,040 --> 00:50:02,040
Speaker 1: reasons why you shouldn't just jump to the conclusion of

874
00:50:02,040 --> 00:50:06,120
Speaker 1: a Silurian civilization, but but there are also some arguments

875
00:50:06,120 --> 00:50:09,600
Speaker 1: against it in some of the specific events that they

876
00:50:09,640 --> 00:50:11,880
Speaker 1: look at. For example, if you know, maybe the best

877
00:50:12,920 --> 00:50:16,520
Speaker 1: possibility is this interesting event in Earth history, the Paleocene

878
00:50:16,520 --> 00:50:19,520
Speaker 1: Eocene thermal maximum. More suddenly there was there was rapid

879
00:50:19,560 --> 00:50:23,640
Speaker 1: global warming and UH and these in these chemical changes

880
00:50:23,680 --> 00:50:27,680
Speaker 1: like with carbon isotopes. They even put some arguments back

881
00:50:27,719 --> 00:50:33,000
Speaker 1: against considering UH civilization as a cause of this global

882
00:50:33,000 --> 00:50:37,200
Speaker 1: warming in Earth's history, because they say, look, the kind

883
00:50:37,200 --> 00:50:40,239
Speaker 1: of global warming caused by our civilization is happening in

884
00:50:40,280 --> 00:50:44,520
Speaker 1: an incredibly rapid fashion over just a few hundred years.

885
00:50:45,040 --> 00:50:49,000
Speaker 1: This actually, though it's it's relatively rapid in geologic terms.

886
00:50:49,440 --> 00:50:53,520
Speaker 1: The the p et M actually happened probably over hundreds

887
00:50:53,520 --> 00:50:58,000
Speaker 1: of thousands of years, which which is incredibly slow if

888
00:50:58,080 --> 00:51:01,160
Speaker 1: you're imagining that civilization was the cause of it, right,

889
00:51:01,360 --> 00:51:03,840
Speaker 1: if you're if you're comparing it to the model of

890
00:51:03,840 --> 00:51:07,839
Speaker 1: of human industrial advancement, it's incredibly slow. So there's not

891
00:51:07,880 --> 00:51:09,600
Speaker 1: only the point that you shouldn't just jump to the

892
00:51:09,640 --> 00:51:13,400
Speaker 1: conclusion of there was a law civilization because it feels cool,

893
00:51:13,440 --> 00:51:16,200
Speaker 1: but like in the specific instances they look at, there

894
00:51:16,200 --> 00:51:19,960
Speaker 1: are some reasons for thinking that's probably not true. I

895
00:51:19,960 --> 00:51:22,319
Speaker 1: don't know, I guess unless those civilizations were like just

896
00:51:22,440 --> 00:51:25,960
Speaker 1: really lazy, Yeah, I mean, you can sort of, you know,

897
00:51:26,000 --> 00:51:28,440
Speaker 1: pull out your sci fi hat and and put it

898
00:51:28,480 --> 00:51:31,000
Speaker 1: on and come up with various ideas of you know,

899
00:51:31,040 --> 00:51:32,680
Speaker 1: for why they might have been this way. Maybe they

900
00:51:32,719 --> 00:51:35,440
Speaker 1: were super long lived. Yeah, they weren't very ambitious, and

901
00:51:35,440 --> 00:51:38,280
Speaker 1: they're like this, note, this is the right level of industrialization,

902
00:51:38,320 --> 00:51:40,479
Speaker 1: and we want to, uh, we need to keep going

903
00:51:40,520 --> 00:51:44,040
Speaker 1: at this rate. I don't know. They didn't reproduce all

904
00:51:44,040 --> 00:51:47,400
Speaker 1: that much. I don't know. I mean that that's ultimately

905
00:51:47,440 --> 00:51:50,640
Speaker 1: one of the problems with with imagining uh, you know,

906
00:51:50,640 --> 00:51:55,239
Speaker 1: other life forms. It's like it's just you know, it's

907
00:51:55,600 --> 00:51:57,600
Speaker 1: you can you can make a case for any number

908
00:51:57,600 --> 00:52:01,560
Speaker 1: of things, um and and try and make it fit

909
00:52:01,840 --> 00:52:04,520
Speaker 1: your your hypothesis. And of course that's not really the

910
00:52:04,520 --> 00:52:06,359
Speaker 1: way to go about it. I mean, not in from

911
00:52:06,360 --> 00:52:10,239
Speaker 1: a scientific perspective, from a sci fi dreaming creative perspective. Yeah,

912
00:52:10,320 --> 00:52:14,920
Speaker 1: go for it, um though, though I guess it does

913
00:52:15,000 --> 00:52:16,560
Speaker 1: kind of come down to the conundrum two at the

914
00:52:16,640 --> 00:52:19,239
Speaker 1: end of the day, like like when does when does

915
00:52:19,280 --> 00:52:23,440
Speaker 1: mere creativity and um and dream weaving become this kind

916
00:52:23,480 --> 00:52:26,319
Speaker 1: of corruption of our thought and uh and and a

917
00:52:26,360 --> 00:52:29,759
Speaker 1: pollution of our ability to understand our place in the

918
00:52:29,800 --> 00:52:32,200
Speaker 1: world and are where we're going in the future and

919
00:52:32,200 --> 00:52:34,279
Speaker 1: where we were in the past. Well, you know, I

920
00:52:34,280 --> 00:52:37,719
Speaker 1: feel like a thread without maybe intending intending to do so.

921
00:52:37,760 --> 00:52:39,880
Speaker 1: That we've pursued A good bit on this podcast is

922
00:52:40,280 --> 00:52:45,280
Speaker 1: understanding the ideally, the difference between your sort of interest

923
00:52:45,360 --> 00:52:49,880
Speaker 1: and imagination and your epistemology. That like that an idea.

924
00:52:50,040 --> 00:52:53,160
Speaker 1: You can like an idea because it's interesting and cool,

925
00:52:53,719 --> 00:52:57,600
Speaker 1: and that doesn't necessarily mean it's true. You know that,

926
00:52:57,800 --> 00:53:00,920
Speaker 1: like that, your your epistemology is probably best to based

927
00:53:00,920 --> 00:53:03,880
Speaker 1: on evidence, and you should be skeptical of things that

928
00:53:04,000 --> 00:53:07,040
Speaker 1: you want to believe because you like them and so forth.

929
00:53:07,360 --> 00:53:10,160
Speaker 1: But it's still totally valid to, like, say, be interested

930
00:53:10,200 --> 00:53:13,200
Speaker 1: in the bicameral mind or whatever because it's a fun idea,

931
00:53:13,719 --> 00:53:16,279
Speaker 1: even if you know, you probably accepted as you know,

932
00:53:16,320 --> 00:53:19,000
Speaker 1: there's not a lot of evidence for it, right right,

933
00:53:19,040 --> 00:53:20,680
Speaker 1: You can you can altomly engage in a number of

934
00:53:20,680 --> 00:53:23,719
Speaker 1: these ideas as as more as art than science, and

935
00:53:23,719 --> 00:53:26,000
Speaker 1: there's certainly nothing wrong with that. Is when you start

936
00:53:26,080 --> 00:53:28,920
Speaker 1: arguing that your art is science, that's where you can

937
00:53:28,920 --> 00:53:31,920
Speaker 1: get into into some trouble. Um. I was reminded in

938
00:53:32,000 --> 00:53:36,320
Speaker 1: all of this of Carl Sagan's approach to ancient aliens

939
00:53:36,440 --> 00:53:39,440
Speaker 1: and ancient astronauts, particularly in the book that he co

940
00:53:39,560 --> 00:53:44,520
Speaker 1: authored with Joseph Shklovsky, Intelligent Life in the Universe. Um.

941
00:53:45,160 --> 00:53:49,200
Speaker 1: In this particular book, you know, they they examine this idea.

942
00:53:49,239 --> 00:53:51,399
Speaker 1: They said, Okay, here's the speculative idea, and we don't

943
00:53:51,400 --> 00:53:53,799
Speaker 1: have evidence that had ever happened. But if it were

944
00:53:53,840 --> 00:53:57,000
Speaker 1: to have happened, what sorts of specific evidence might we

945
00:53:57,080 --> 00:54:00,000
Speaker 1: look for? And in this case, we're talking about science

946
00:54:00,040 --> 00:54:03,680
Speaker 1: ends that are evident in ancient religions and uh and

947
00:54:03,719 --> 00:54:06,399
Speaker 1: so forth. Uh. And I thought that was a great

948
00:54:06,400 --> 00:54:10,480
Speaker 1: treatment of that question. Uh. And against Sagan's treatment reminds

949
00:54:10,520 --> 00:54:13,640
Speaker 1: me of the treatment given in this paper by these authors.

950
00:54:13,880 --> 00:54:16,280
Speaker 1: But of course Segand had to come back and continue

951
00:54:16,320 --> 00:54:20,239
Speaker 1: to argue with the ancient alien people who were, you know,

952
00:54:20,360 --> 00:54:22,919
Speaker 1: very much going off in their own director is true, ye, yeah,

953
00:54:22,960 --> 00:54:26,120
Speaker 1: and pushing pushing art as science, and Sagan having to

954
00:54:26,120 --> 00:54:28,120
Speaker 1: remind them like, no, I love art as much as

955
00:54:28,120 --> 00:54:30,960
Speaker 1: the next guy, but here's how we approach this from

956
00:54:31,000 --> 00:54:34,600
Speaker 1: a scientific perspective. Well, I mean, I think the important

957
00:54:34,640 --> 00:54:37,239
Speaker 1: thing about this stuff, like Sagan's work on that or

958
00:54:37,440 --> 00:54:39,279
Speaker 1: or or the paper we're looking at here is it's

959
00:54:39,360 --> 00:54:41,920
Speaker 1: good too when you're when you're exploring it like a

960
00:54:42,000 --> 00:54:45,560
Speaker 1: tantalizing and juicy idea. It's a good idea to have

961
00:54:46,200 --> 00:54:49,920
Speaker 1: criteria for what would be good evidence of such a

962
00:54:50,000 --> 00:54:54,000
Speaker 1: thing before you're actually looking at individual evidence in cases,

963
00:54:54,000 --> 00:54:56,080
Speaker 1: because if you look at the evidence first and then

964
00:54:56,120 --> 00:54:58,480
Speaker 1: you try to come up with criteria, you're gonna have

965
00:54:58,520 --> 00:55:01,160
Speaker 1: a tendency to want to fit your criteria or whatever

966
00:55:01,239 --> 00:55:04,880
Speaker 1: evidence you've already got. The cherry picking model or what

967
00:55:05,000 --> 00:55:08,560
Speaker 1: is it the other name of the barn wall fallacy

968
00:55:08,680 --> 00:55:11,000
Speaker 1: or something like that. Remember, the idea is like, you know,

969
00:55:11,560 --> 00:55:13,359
Speaker 1: somebody says, you know, I'm a great shot, and so

970
00:55:13,400 --> 00:55:15,399
Speaker 1: they shoot at the side of a barn, and then

971
00:55:15,719 --> 00:55:17,440
Speaker 1: they go up, they walk up to their bullet hole,

972
00:55:17,480 --> 00:55:19,640
Speaker 1: and then they draw a bulls eye perfectly around it.

973
00:55:20,040 --> 00:55:21,880
Speaker 1: That's that's a great point. That's that's a great way

974
00:55:21,920 --> 00:55:24,080
Speaker 1: of looking at it. All Right, Well, I guess we're

975
00:55:24,080 --> 00:55:26,120
Speaker 1: gonna go ahead and wrap this episode up. But we'd

976
00:55:26,160 --> 00:55:28,239
Speaker 1: love to hear from everyone out there. I love to

977
00:55:28,239 --> 00:55:31,960
Speaker 1: hear from any doctor who fans who have some additional

978
00:55:32,200 --> 00:55:36,520
Speaker 1: information they want to share about the Silurians. And various

979
00:55:36,520 --> 00:55:39,880
Speaker 1: related um species that have popped up in that show.

980
00:55:40,440 --> 00:55:44,040
Speaker 1: And perhaps you have specific thoughts about about you know,

981
00:55:44,120 --> 00:55:47,400
Speaker 1: just this this basic you know view, uh, and what

982
00:55:47,440 --> 00:55:52,040
Speaker 1: it reveals about humanities uh place on Earth right now,

983
00:55:52,200 --> 00:55:57,120
Speaker 1: and what technological civilization is doing to the planet, and

984
00:55:57,480 --> 00:55:59,440
Speaker 1: just you know, ultimately, what kind of a you know,

985
00:55:59,480 --> 00:56:02,120
Speaker 1: a small lip a week signal we may be in

986
00:56:02,120 --> 00:56:05,400
Speaker 1: the future as opposed to this kind of lasting thing

987
00:56:05,520 --> 00:56:09,719
Speaker 1: that we sometimes imagine that human civilization is. I'm going

988
00:56:09,800 --> 00:56:13,239
Speaker 1: to say, I hope that I'll be optimistic, so I

989
00:56:13,239 --> 00:56:15,960
Speaker 1: hope we do stick around. I hope we attenuate the

990
00:56:16,080 --> 00:56:19,480
Speaker 1: kinds of geologic signal we leave due to climate change,

991
00:56:19,480 --> 00:56:22,120
Speaker 1: in chemical alteration of the atmosphere and all you know

992
00:56:22,239 --> 00:56:25,800
Speaker 1: stuff like that, uh, you know, heavy metal pollutions and things,

993
00:56:25,880 --> 00:56:28,920
Speaker 1: and that we the signal of our civilization can always

994
00:56:28,960 --> 00:56:32,000
Speaker 1: be charted against the geologic record because of the continuance

995
00:56:32,040 --> 00:56:35,200
Speaker 1: of Doctor Who Seasons. So when we're on the like,

996
00:56:35,320 --> 00:56:37,960
Speaker 1: you know, eventually we'll get into the exponential notation of

997
00:56:38,000 --> 00:56:42,000
Speaker 1: the Doctor who Seasons. Yeah yeah, yeah. Well, one day

998
00:56:42,280 --> 00:56:45,600
Speaker 1: some sort of ancient uh or rather some sort of

999
00:56:45,800 --> 00:56:48,839
Speaker 1: far flung future civilization will look back and say, look,

1000
00:56:49,520 --> 00:56:52,040
Speaker 1: clearly they knew what they were doing. Uh, they were

1001
00:56:52,080 --> 00:56:55,560
Speaker 1: able to do you know, some three million years of

1002
00:56:55,640 --> 00:56:58,360
Speaker 1: doctor who though maybe at a certain point the doctor

1003
00:56:58,440 --> 00:57:00,440
Speaker 1: will be a robot and the enemy, as will be

1004
00:57:00,600 --> 00:57:04,440
Speaker 1: will be organics. And I don't know, Yeah, I wonder

1005
00:57:04,800 --> 00:57:06,960
Speaker 1: at what point do we get a robot doctor. I mean,

1006
00:57:07,000 --> 00:57:10,640
Speaker 1: they they're they've only recently really been been been mixing

1007
00:57:10,719 --> 00:57:14,120
Speaker 1: up the casting on that role. All right, Well, let

1008
00:57:14,200 --> 00:57:16,000
Speaker 1: us know in the meantime, if you want to listen

1009
00:57:16,040 --> 00:57:17,720
Speaker 1: to other episodes of Stuff to Blow Your Mind, we

1010
00:57:17,760 --> 00:57:20,040
Speaker 1: have core episodes on Tuesdays and Thursdays and the Stuff

1011
00:57:20,040 --> 00:57:23,280
Speaker 1: to Blow Your Mind podcast feed. On Monday's we do

1012
00:57:23,360 --> 00:57:26,560
Speaker 1: listener mail, where we hear from from you, the listeners,

1013
00:57:26,760 --> 00:57:29,360
Speaker 1: and we we read your various listener mails, always a

1014
00:57:29,360 --> 00:57:32,200
Speaker 1: good time. On Wednesday's we do a short form artifact

1015
00:57:32,320 --> 00:57:34,360
Speaker 1: or monster fact, and then on Fridays we do Weird

1016
00:57:34,360 --> 00:57:37,480
Speaker 1: How Cinema. That's our time to set aside most serious

1017
00:57:38,320 --> 00:57:41,800
Speaker 1: issues and just talk about a weird film. Huge thanks

1018
00:57:41,880 --> 00:57:44,880
Speaker 1: as always to our excellent audio producer Seth Nipolis Johnson.

1019
00:57:45,280 --> 00:57:46,880
Speaker 1: If you would like to get in touch with us

1020
00:57:46,880 --> 00:57:49,320
Speaker 1: with feedback on this episode or any other to suggest

1021
00:57:49,440 --> 00:57:51,320
Speaker 1: topic for the future, or just to say hello. You

1022
00:57:51,360 --> 00:57:54,240
Speaker 1: can email us at contact that Stuff to Blow Your

1023
00:57:54,240 --> 00:58:04,400
Speaker 1: Mind dot com. Stuff to Blow Your Mind is production

1024
00:58:04,480 --> 00:58:07,200
Speaker 1: of I Heart Radio. For more podcasts for my heart Radio,

1025
00:58:07,440 --> 00:58:10,120
Speaker 1: visit the i heart Radio app, Apple Podcasts, or wherever

1026
00:58:10,160 --> 00:58:23,400
Speaker 1: you listen to your favorite shows.